[bug #57836] grotty's adjustment algorithm is not diversion-aware

[Dave]

URL:
  <https://savannah.gnu.org/bugs/?57836>

                 Summary: grotty's adjustment algorithm is not diversion-aware
                 Project: GNU troff
            Submitted by: barx
            Submitted on: Mon 17 Feb 2020 01:43:04 AM CST
                Category: Device - others
                Severity: 3 - Normal
              Item Group: Incorrect behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None

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Details:


$ groff -Tascii tty_example | head -14
For  TTY  output  with  full justification, grotty pads by adding
extra spaces alternating every line left-to-right  and  right-to-
left,  as  can be seen in this paragraph.  This helps to preserve
overall uniform grayness  throughout  the  text,  as  well  as  a
monospaced typeface allows.

But  diversions  requiring  adjustment apparently are included in
this  sequence  even  if they are not output right away (or ever,
for  that  matter).   This  means that a number of closely spaced
diversion  definitions  can  break  grotty's balancing algorithm,
putting  all  the  space  on  the same end of every line, as this
paragraph demonstrates.


$ cat tty_example
.nh
For TTY output with full justification, grotty pads by
adding extra spaces alternating every line left-to-right and
right-to-left, as can be seen in this paragraph.  This helps
to preserve overall uniform grayness throughout the text,
as well as a monospaced typeface allows.
.
.sp
.
But diversions requiring adjustment apparently are included in
this sequence even if they are not output right away (or ever,
.box dummy
This is some dummy text, enough to kick in the adjustment algorithm.
.box
for that matter).  This means that a number of closely spaced
.box dummy
This is some dummy text, enough to kick in the adjustment algorithm.
.box
diversion definitions can break grotty's balancing algorithm,
.box dummy
This is some dummy text, enough to kick in the adjustment algorithm.
.box
putting all the space on the same end of every line, as this
.box dummy
This is some dummy text, enough to kick in the adjustment algorithm.
.box
paragraph demonstrates.
$ groff -Tascii --version
GNU groff version 1.22.4.74-b400-dirty
Copyright (C) 2018 Free Software Foundation, Inc.
GNU groff comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of groff and its subprograms
under the terms of the GNU General Public License.
For more information about these matters, see the file
named COPYING.

called subprograms:

GNU grotty (groff) version 1.22.4.74-b400-dirty
GNU troff (groff) version 1.22.4.74-b400-dirty





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